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Old 12-24-2013, 03:05 PM
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Normal Oil Pressure in a 4.0 and Rough Idle

So I was talking to a friend about his 5.0 Foxbody and he said something about him needing to rebuild his engine because his oil pressure was running too high (60 psi). And that got me paranoid about my WJ. She runs about 40psi in the city but on the Highway at 75mph shes running about 60psi. Is this normal? That's the pressure shes had since I bought her at 126K, she now has 135K.

Second thing ive got a rough idle. Just changed the plugs in her yesterday thinking that would solve the problem. The ones I pulled out looked perfect, they weren't worn out too bad but I just put the new ones in anyway, but the problem persisted. What could it be? I was thinking maybe motor mounts because my T-Case mount needs to be replaced and the motor mounts do look worn out. However sometimes I do notice a slight miss, and whenever I push the gas down it almost hesitates. Like I push down the gas she acts like she wants to stall for just a second then she accelerates. I just am stuck on the problem because all the plugs looked normal, and they all looked the same. Maybe injectors? Fuel filter? I would post pictures of the plugs but the picture uploader wont work. One of my friends suggested a clogged cat or muffler but that's not the problem because im running piped, only have the pre cats coming off the manifold, gutted the main cat, and cut off the muffler. And gutting the cat has nothing to do with the situation because the O2's are before the precats.

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Old 12-24-2013, 03:40 PM
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Re: Normal Oil Pressure in a 4.0 and Rough Idle

Have you cleaned the throttle body and IAT? Carbon buildup in the TB will cause strange idle behavior. Also, vacuum leads will cause erratic idle behavior.

As for oil pressure, I cannot help you but would use your experience with the oil pressure on your WJ as the reference and let the Ford specs for the Ford engines.
2004 Columbia Edition WJ 4.7 HO
RB4/Moog HD Steering Stabilizer/PML trans pan 10304/ Autometer trans temp and oil pressure gauge/UpCountry springs & OME 10MM Spacers/Bilstein shocks/Rubicon Moabs/255/65r17 Cooper Discoverer AT3/Factory chrome tow hooks/Mopar hitch & a loose nut behind the wheel
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